The Effects Of Vegetation Recovery On Microbial Communities Across The Secondary Succession In The Loess Plateau

The Loess Plateau is the most serious soil erosion ecosystem with the most fragile ecological environment in our country.In recent 20 years,soil quality is improved significantly by returning farmland into forest and grass to undergo soil remediation and ecosystem reconstruction.In this study,we investigate the response of vegetation types and years of restoration,different root-associated compartments,environmental factors to soil microbial community and the influencing mode of plants and environmental factors on microbial community via the second generation of high-throughput sequencing.The influence of vegetation types,years of restoration and environmental factors on soil bacterial and fungal community were studied.The results of 16 S rRNA gene showed phylum Proteobacteria,Actinobacteria and Acidobacteria were dominant bacterial taxa,which accounted for 50%~64%.ITS gene sequencing appeared that phylum Ascomycota,Basidiomycota,Zygomycota and Glomeromycota were dominant fungal populations,and Ascomycota accounted for 50%-80%.Based on the microbial community diversity analysis of 16 S rRNA sequencing,environmental factors contributed the maximum impact,of which organic matter,total nitrogen and available potassium effected profoundly in shaping microbial community diversity.Besides,the years of vegetation restoration was the second contributing factor.As for fungal community diversity variation,different vegetation types have the most impact and the second influences were years of the vegetation restoration and environmental factors.Furthermore,there were significant variation between Robinia pseudoacaia and other vegetations,14 and 40 years,14 and 33 years.In totally,vegetation types and years of restoration,environmental factors shaped the diversity of microbial community together.And 16 S rRNA microbial community analysis indicated that it was effected by environmental factors mostly,while fungal community was influenced by vegetation types mainly.We analyzed the fungal community structure of different root-associated compartments of woody plants and herbaceous plants.The results showed that the influence of different root-associated compartments on fungal community structure was small.No obvious ?-diversity variation in bulk soil,root zone and rhizosphere of woody and herbaceous plants.The community variation based on Bray-Curtis distance just existed between endosphere and other root-associated compartments.We also analyzed the bacterial and Archaea community structure of different root-associated compartments of woody plants and herbaceous plants.The results showed accordant ?-diversity variation patterns on woody plants and herbaceous plants with highest ?-diversity in bulk soil and root zone as well as decreasing gradually ?-diversity in rhizosphere and endosphere.The community variation based on Bray-Curtis distance suggested no obviously change between bulk soil and root zone of woody plants,while the variations among other root-associated compartments were significant.Moreover,community variation based on Bray-Curtis distance of herbaceous plants varied significantly between any two root-associated compartments.The sequencing results exhibited the relative abundance of Acidobacteria declined among bulk soil-root zone-rhizosphere-endosphere of woody plans,while the relative abundance of Proteobacteria presented increasing tendency.The relative abundance of Actinobacteria decreased from bulk soil-root zone-rhizosphere gradually,and reduced in endosphere of woody plans substantially.On herbaceous plants,the relative abundance of Acidobacteria,Actinobacteria and Proteobacteria showed no variation in bulk soil and root zone,and Acidobacteria decreased significantly in rhizosphere and endosphere,Proteobacteria and Actinobacteria increased slightly in rhizosphere compartment.Besides,the relative abundance of Acidobacteria was low,while Proteobacteria was highest in endosphere.The co-occurrence network patterns analysis indicated that complexity emerged an increasing trend among bulk soil-root zone-rhizosphere-endosphere,and the increasing trend of complexity among bulk soil-root zone-rhizosphere in woody plants was slower than herbaceous plants.